Passport valid for travel to the United States – Your passport must be valid for at least six months beyond your period of stay in the United States (unless exempt by country-specific agreements). Each individual who needs a visa must submit a separate application, including any family members listed in your passport.
Nonimmigrant Visa Application, Form DS-160 confirmation page.
Application fee payment receipt, if you are required to pay before your interview.
Photo – You will upload your photo while completing the online Form DS-160. If the photo upload fails, you must bring one printed photo in the format explained in the Photograph Requirements.
After the interview
The purpose of your trip,
Your intent to depart the United States after your trip, and/or
Your ability to pay all costs of the trip.
Very straight forward.